Back to EveryPatent.com
United States Patent |
5,093,206
|
Schoenbeck
|
March 3, 1992
|
Curable laminated article of EPDM elastomer and ethylene-containing
polymer
Abstract
A curable laminated article, useful for roofing application, comprising at
least two layers, each layer comprising a blend of (a) 50-80% by weight of
an ethylene/propylene/nonconjugated diene elastomer and (b) 20-50% by
weight of an ethylene-containing polymer selected from the group
consisting of polyethylene, an ethylene alpha-monoolefin copolymer wherein
the monoolefin contains from 3-12 carbon atoms and is present in amounts
of 2-8% by weight, and as ethylene/vinyl acetate copolymer having a vinyl
acetate content up to about 10% by weight, and wherein each alternate
layer contains either elemental sulfur as the crosslinking agent for the
elastomer or a cure accelerator so that the elastomer in the laminated
article subsequently cures when elemental sulfur and the accelerator in
each layer migrate to an adjacent layer when the laminate is exposed to
elevated temperatures.
Inventors:
|
Schoenbeck; Melvin A. (Wilmington, DE)
|
Assignee:
|
E. I. Du Pont de Nemours and Company (Wilmington, DE)
|
Appl. No.:
|
490923 |
Filed:
|
March 9, 1990 |
Current U.S. Class: |
428/521; 428/141; 428/500; 525/222 |
Intern'l Class: |
B32B 027/32 |
Field of Search: |
428/521,500,141
525/222
|
References Cited
U.S. Patent Documents
2611721 | Jun., 1949 | Brees | 154/8.
|
3372078 | May., 1968 | Fausti et al. | 156/306.
|
3834932 | Sep., 1974 | Brandl | 117/47.
|
4666785 | May., 1987 | Crepeau | 428/521.
|
Foreign Patent Documents |
2350 | Jan., 1982 | JP | 525/222.
|
Primary Examiner: Buffalow; Edith L.
Attorney, Agent or Firm: Evans; Craig H.
Claims
I claim:
1. A curable laminated article, useful for roofing application, comprising
at least two layers, each layer comprising a blend of (a) 50-80% by weight
of an ethylene/propylene/nonconjugated diene elastomer and (b) 20-50% by
weight of an ethylene-containing polymer selected from the group
consisting of polyethylene, ethylene alpha-monoolefin copolymers wherein
the monoolefin contains from 3-12 carbon atoms and is present in amounts
of 2-8% by weight, and ethylene/vinyl acetate copolymers having vinyl
acetate contents up to about 10% by weight, and wherein each alternate
layer contains either elemental sulfur as the crosslinking agent for the
elastomer or a cure accelerator so that the elastomer in the laminated
article subsequently cures when elemental sulfur and the accelerator in
each layer migrate to an adjacent layer when the laminate is exposed to
elevated temperatures.
2. A laminated article of claim 1 wherein the ethylene/propylene/diene
elastomer contains 50-75% by weight ethylene units.
3. A laminated article of claim 1 wherein the ethylene-containing polymer
is polyethylene.
4. A laminated article of claim 1 wherein the ethylene-containing polymer
is an ethylene/butene copolymer.
5. A laminated article of claim 1 wherein the ethylene-containing polymer
is an ethylene/vinyl acetate copolymer.
6. A laminated article of claim 1 wherein the elastomer is an
ethylene/propylene/1,4-hexadiene elastomer.
7. A laminated article of claim 1 wherein the elastomer is an
ethylene/propylene/ethylidene norbornene elastomer.
8. A laminated article of claim 4 wherein the elastomer is an
ethylene/propylene/norboradiene/diene tetrapolymer.
9. A laminated article of claim 8 wherein the elastomer contains 50-75% by
weight ethylene units.
10. A laminated article of claim 1 wherein the accelerator is a salt of a
dialkyldithiocarbamate.
11. A laminated article of claim 10 wherein the accelerator is zinc
dibutyldithiocarbamate.
12. A laminated article of claim 10 wherein the dialkyldithiocarbamate is
zinc dimethyldithiocarbamate.
13. A laminated article of claim 1 wherein zinc oxide is present in a
layer.
14. A laminated article of claim 9 wherein the elastomer is an
ethylene/propylene/1,4-hexadiene/norbornadiene tetrapolymer.
15. A laminated article of claim 2 wherein the ethylene-containing polymer
is an ethylene/butene copolymer and wherein the accelerator is a salt of a
dialkyldithiocarbamate.
16. A laminated article of claim 4 wherein the elastomer contains about
65-72% by weight ethylene units.
Description
BACKGROUND OF THE INVENTION
This invention relates to sheeting or membrane materials based on blends of
ethylene/propylene/nonconjugated diene elastomers (EPDM) and
ethylene-containing polymers which combine the properties of durability
and seamability and are useful for covering roofs of building structures.
Thermoset EPDM elastomer compositions are very weather-resistant and they
are used extensively as roofing membranes. However, the adhesive systems
required to bond connecting sheets of the thermoset roofing provide only
marginally adequate bond strength and they add significantly to the
installation cost of the roofing membranes because of the labor required.
The establishment of strong water-tight seams between adjacent sheets of
roofing material is, of course, extremely important in such applications.
The seams of the connecting sheets are often subjected to high winds,
heavy rains, and snow and ice storms and they must be capable of
withstanding the stresses generated by such adverse weather conditions. In
addition, the seams of the connecting sheets used on flat roofs are
further subjected to additional stress from the pooling of water, which
often goes through alternating cycles of freezing and thawing. Finally,
foot traffic across the roof covered with sheets of thermoset EPDM
elastomers also contributes to considerable stress on the seams over the
lifetime of the roofing membrane which may exceed 20 years.
Alternatively, thermoplastic EPDM compositions have been proposed for
roofing membranes because they can be seamed rapidly by the application of
heat and pressure. However, these compositions have not been used
successfully because they soften excessively when exposed to direct
sunlight during the warm weather months and thus require careful handling
during installation and because they lack the toughness of cured sheets.
Improving the hot strength of thermoplastic EPDM by blending it with other
higher melting polymeric materials is only a partial solution to these
problems. Although the hot strength of the blend is adequate for
installation of the roofing membrane, the possibility of damage from foot
traffic still exists each summer during hot weather.
Thus there is a need in the roofing membrane industry for a durable, heat
seamable composition that does not require the application of adhesives
containing organic solvent to the edges of the film or membrane to bond or
seal the films together and also provides membranes having adequate
strength for installation and resistance to damage from foot traffic.
SUMMARY OF THE INVENTION
The present invention is directed to a laminated article, especially useful
for roofing applications, which comprises at least two layers, each layer
comprising a blend of (a) 50-80% by weight, preferably 60-75% weight
percent, of an ethylene/propylene/non-conjugated diene elastomer and (b)
20-50% by weight, preferably 25-40% by weight, of an ethylene-containing
polymer selected from the group consisting of polyethylene, ethylene
alpha-monoolefin copolymers wherein the alpha-monoolefin contains 3-12
carbon atoms and is present in an amount of about 2-8% by weight and
ethylene/vinyl acetate copolymers having vinyl acetate contents up to
about 10% by weight, and wherein each alternate layer contains either
elemental sulfur as the crosslinking agent for the elastomer or a cure
accelerator so that the elastomer in the laminated article subsequently
cures when elemental sulfur and the accelerator in each layer migrate to
an adjacent layer when the laminate is exposed to elevated temperatures.
The EPDM elastomer can contain from 50-75 percent by weight ethylene, and
preferably the elastomer contains from about 65-72% by weight ethylene.
Preferably, the EPDM is a terpolymer of ethylene, propylene, and
1,4-hexadiene or ethylidene norbornene. Another preferred EPDM elastomer
is a tetrapolymer of ethylene, propylene, 1,4-hexadiene and norbornadiene.
To increase the rate and level of cure zinc oxide is usually present in at
least one layer, preferably in all layers.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
The curable laminated article of the present invention has two or more
layers wherein one layer(s) contains elemental sulfur and the adjacent
layer(s) contains the accelerator. Each layer contains a blend of the EPDM
elastomer and an ethylene-containing polymer. The layered or laminated
structure and the composition of the polymer blend provide the strength
necessary for the laminate to be used, especially as a roofing membrane.
The curative system, that is, the elemental sulfur crosslinking agent and
the accelerator, slowly migrates between the layers when the laminate is
exposed to elevated temperature, for example, temperatures exceeding
70.degree. C. for about 30 days and thereby forms a cured, tough durable
membrane. When the curable laminate is installed on a roof, and ambient
temperatures are of the order of 20.degree.-25.degree. C. and temperatures
on a roof covered by the laminated article reach about
70.degree.-80.degree. C. for at least several hours per day, the laminate
cures in about 40-60 days. During installation of the laminated roofing
membrane, the membranes containing two or more layers are joined together
by simply heat seaming in a conventional manner the edges of adjoining
sheets.
Each of the layers of the curable laminated article comprises a blend of
EPDM elastomer and an ethylene-containing polymer. The EPDM that is
present in the blend in amounts of from 50-80% by weight, preferably
60-75% by weight, can be any ethylene/propylene/diene terpolymer or
tetrapolymer elastomer of the EPDM type. EPDM elastomers are copolymers of
ethylene and propylene and a nonconjugated diene having one reactive
double bond. They may, in addition, contain a minor amount of a second
diene, which may have two reactive double bonds. The non-conjugated dienes
of the first type include 1,4-hexadiene; 2-methyl-1,5 hexadiene;
1,9-octadecadiene; dicyclopentadiene; tricyclopentadiene;
5-ethylidene-2-norbornene; or 5-methylene-2-norbornene. Preferred dienes
having one reactive double bond are 1,4-hexadiene and ethylidene
norbornene. The non-conjugated dienes of the second type include
norbornadiene; 1,4-pentadiene; 1,5-hexadiene; 1,7-octadiene;
1,20-heneicosadiene; or 5-(5-hexenyl)-2-norbornene, preferably
norbornadiene. The EPDM elastomers which are suitable for use in the
laminated articles of this invention contain about 50-75 weight percent of
ethylene, preferably 65-72 %, and 1-6 weight percent of a diene or
combination of dienes, the remainder being substantially propylene. The
preferred EPDM elastomers are those which are highly crystalline and have
ethylene contents of at least 65% by weight because such elastomers
provide improved strength to the blended compositions while they are still
uncured.
The polymer blend forming a single layer of the resulting laminate also
contains from 20-50% by weight, preferably 25-40% by weight, of a second
ethylene-containing polymer selected from the group consisting of (a)
polyethylene, (b) ethylene/alpha-monoolefin copolymers wherein the
alpha-monoolefin contains 3-12 carbon atoms, preferably 4-8 carbon atoms,
and is present in an amount of from about 2-8% by weight and (c)
ethylene/vinyl acetate copolymers containing up to 10% by weight vinyl
acetate, usually 3-9% by weight. The polyethylene used in the blend can be
any type, that is, high, low, or medium density polyethylene. Preferably,
the polyethylene used has a density of from 0.92-0.94 g/cc. Representative
ethylene/alpha-monoolefin copolymers include ethylene/propylene,
ethylene/butene, ethylene/hexene, ethylene octene, and ethylene heptene.
Ethylene/butene is preferred. The addition of the ethylene-containing
polymers that are compatible with and incorporated in the EPDM elastomer
raises the modulus of the elastomer and hence the strength of the
elastomer. Usually, the uncured laminated membranes have a modulus at 50%
elongation of at least 1.4 MPa (200 psi) when measured in the transverse
direction at 70.degree. C.
It is an important feature of the invention that the curative and
accelerator portions of the crosslinking system be present in alternate
layers. Thus, elemental sulfur is present in one layer(s) and the
accelerator is present in the adjacent layer(s). Accordingly, during
compounding of the elastomer blend used for each layer, either sulfur or
accelerator is present.
Separation of the curing system precludes scorching of the composition
during the compounding and calendering processes and, consequently,
subsequent seamability is not adversely affected. When the laminates are
installed on a roof, the adjacent laminates are easily heat-sealed at
their edges and the entire laminated membrane slowly cures in place by
diffusion of the elemental sulfur and accelerator into adjacent layers
with subsequent curing as a result of elevated temperatures.
The elastomer compositions which are used to form the curative-containing
layer(s) have incorporated therein about 0.5-2 parts elemental sulfur per
100 parts total polymer.
Accelerators are incorporated into the elastomer blend compositions used to
form the alternate layer(s) of the laminate in amounts of from about 1-4
parts accelerator per 100 parts total polymer. Conventional accelerators
that are used in curing systems for EPDM elastomers can be used.
Representative accelerators include salts of dialkyldithiocarbamates such
as zinc dibutyldithiocarbamate, zinc dimethyldithiocarbamate, zinc
diethyldithiocarbamate, bismuth dibutyldithiocarbamate, copper
dimethyldithiocarbamate, selenium diethyldithiocarbamate, lead
dimethyldithiocarbamate, tellurium diethyldithiocarbamate, cadium
diethyldithiocarbamate and thiuram monosulfides such as tetramethylthiuram
monosulfide and tetrabutylthiuram monosulfide.
The blend of EPDM elastomer and ethylene-containing polymer containing
accelerator can contain, and preferably does contain, a vulcanization
promoter that assists in further accelerating the cure of the EPDM
elastomer when the accelerator and elemental sulfur migrate to a layer but
which does not itself result in cure of the EPDM elastomer. Indeed, the
action of these vulcanization promoters is so weak that they can be
incorporated in the blend of EPDM elastomer and ethylene-containing
polymer that contains elemental sulfur and scorching will not occur if
processing temperatures do not exceed 130.degree. C. These vulcanization
promoters include benzothiazoles such as 2-mercaptobenzothiazole,
benzothiazyl disulfide, and 2-mercaptothiazoline. These vulcanization
promoters can be incorporated in the polymer blend in amounts of from
about 0.5-3 parts per 100 parts total polymer.
Metal oxides are usually present in the curative system. Representative
metal oxides include zinc oxide, lead oxide, bismuth oxide, cadmium oxide
and calcium oxide. Zinc oxide is almost always the metal oxide of choice
because of its effectiveness and lack of toxicity. Usually such metal
oxides are added to the polymer composition in amounts of from 2 to 10
parts/100 parts total polymer. Many accelerators and vulcanization
promoters react with zinc oxide to form salts of even greater
vulcanization activity. Zinc oxide itself acts as a vulcanization
promoter, speeding the rate of reaction of elemental sulfur with the
unsaturated cure sites in the EPDM elastomer.
Other ingredients such as low volatility paraffinic or naphthenic
processing oils, such as Sunpar 2280 and Shellflex 790 can be incorporated
in the blend in amounts usually from 10-60 parts per 100 parts total
polymer. Fillers such as carbon black and mineral fillers can be
incorporated in the polymer blend in amounts usually from 50-200 parts per
100 parts total polymer.
In order to form the laminates of the present invention the compounded
material containing elemental sulfur as the curative and the compounded
material containing the accelerator are formed into a multi-layered sheet.
This can be accomplished either by first forming one of the sheets on a
calendar, and subsequently calendering the second sheet directly onto the
first sheet. Calendar roll temperatures between about
120.degree.-160.degree. C. are used to calendar these sheets.
Alternatively, when a four-roll calendar is used, a two-layer laminate can
be formed by adding one of the blend compositions directly to the feed nip
between rolls one and two, and the other blend composition is added to the
feed nip between rolls three and four. By directing the sheet from rolls
one and two around roll two, and the sheet from rolls three and four
around roll three, the two sheets can be laminated together as they are
pressed together between rolls two and three.
Generally, the laminates contain two or three layers but can contain of the
order of five. When forming the laminate the layers containing sulfur
curative and those containing accelerator are placed in alternate plies.
The thickness of an individual layer is from about 0.13-1.3 mm, and
preferably 0.25-1.0 mm and the thickness of the multi-layered structure
can be from about 0.5-4.0 mm, preferably 1.0-2.0 mm.
The Mooney scorch value for each layer of the uncured laminate usually is
at least about 30 minutes to a 10 point rise measured at 150.degree. C.
using ASTM D-1646, small rotor. Also, usually the cure rate of the
laminate itself is such that it has a tensile strength at 70.degree. C. of
at least about 2.5 MPa and a modulus at 50% elongation of at least about
2.0 in the transverse direction after exposure in an oven heated to
70.degree. C. for 30 days.
The following examples in which parts are by weight, unless otherwise
indicated, further illustrate embodiments of the invention.
POLYMERS
Polymer Composition A
70 parts:
71% Ethylene/Propylene/3.7% 1,4-Hexadiene/0.9% Norbornadiene
Inherent viscosity: 2.2
30 parts:
Ethylene-butene copolymer
Wt. ratio 94/6, Density 0.924 g/cc
Melt index: 4.0 dg/min. (ASTM D 1238
Condition 190/2.16)
Polymer Composition B
70 parts:
71% Ethylene/Propylene/3.7% 1,4-Hexadiene/0.9% Norbornadiene
Inherent viscosity: 2.2
30 parts:
Ethylene/vinyl acetate
Vinyl acetate content 9%
Melt index 2.0 dg/min. (ASTM D1238 Condition 190/2.16)
Polymer Composition C
70 parts:
72% Ethylene/Propylene/4.6% Ethylidene norbornene
Inherent viscosity: 2.3
30 parts:
Ethylene-butene copolymer
Wt. ratio 94/6, Density 0.924 g/cc
Melt index: 4.0 dg/min. (ASTM D 1238, Condition 190/2.16)
Polymer Composition D
60 parts:
71% Ethylene/Propylene/3.7% 1,4-Hexadiene/0.9% Norbornadiene
Inherent viscosity: 2.2
40 parts:
Ethylene-butene copolymer
Wt. ratio 94/6 Density 0.924 g/cc
Melt index: 4.0 dg/min. (ASTM D 1238, Condition 190/2.16)
Polymer Composition E
75 parts:
70% Ethylene/Propylene/3.7% 1,4-Hexadiene/0.14% Norbornadiene
Inherent viscosity: 2.0
25 parts:
Polyethylene
Density 0.920 g/cc
Melt index: 1.1 dg/min. (ASTM D 1238, Condition 190/2.16)
EXAMPLE 1
An elastomer compound IA was prepared by mixing 100 parts Polymer
Composition A, 140 parts carbon black, 30 parts paraffinic petroleum oil
(Sunpar 2280), 0.16 parts stearic acid, 3 parts zinc oxide and 1 part
elemental sulfur in a Banbury mixer with rotor speed at 80 rpm. The
compound was dumped from the mixer when the temperature reached
120.degree.-130.degree. C. Mooney scorch of the compound was measured at
150.degree. C. according to ASTM D-1646 using the small rotor. The minimum
was 30 and after 30 minutes there was a 5 point rise.
In a similar manner elastomer composition 1B was prepared by mixing 100
parts Polymer Composition A, 140 parts carbon black, 30 parts paraffinic
petroleum oil, 0.1 part stearic acid, 3 parts zinc oxide, 1 part
mercaptobenzothiazole and 1 part zinc dibutyldithiocarbamate. The Mooney
scorch of the compound was measured as described above and the minimum was
30 and after 30 minutes there was a zero point rise.
A two-layer laminate was produced by first calendering a 0.57 mm thick
sheet of elastomer compound 1A between calendar rolls heated to
130.degree. C. and then calendering a 0.57 mm thick sheet of elastomer
compound 1B directly onto the first sheet between calendar rolls heated to
130.degree. C. This formed a 1.14 mm thick two layer structure.
Physical properties of the curable laminate were measured at 23.degree. C.
and at 70.degree. C. according to ASTM D 412 in both the machine and
transverse directions. Results are shown in Table I.
TABLE I
______________________________________
Machine Transverse
Direction
Direction
______________________________________
Properties Measured at 23.degree. C.
Modulus at 50% Elongation, (MPa)
6.9 5.2
Tensile Strength, (MPa)
9.9 8.5
Elongation at Break, (%)
290 400
Properties Measured at 70.degree. C.
Modulus at 50% Elongation, (MPa)
2.1 1.4
Tensile Strength, (MPa)
2.5 1.6
Elongation at Break, (%)
250 280
______________________________________
The edges of two laminates were seamed together with a mechanically driven
hot air seamer with air heated to 490.degree. C. The speed of the seamer
was 1.2 m per minute. The peel adhesion was 1.4 kN/m on the uncured
sample. After 7 days in a 70.degree. C. oven the peel adhesion was 6.7
kN/m.
Laminate samples prepared as described above were placed in an oven heated
to 70.degree. C. The modulus at 50% elongation measured at 70.degree. C.
in the transverse direction was determined after the times shown in Table
II.
TABLE II
______________________________________
Modulus at 50% Elongation, (MPa)
______________________________________
0 Days 1.4
After 30 Days
2.8
After 60 Days
3.0
After 90 Days
3.2
______________________________________
A three-layer laminate of elastomer composition 1A and 1B, described above,
was prepared by first calendering (a) 0.57 mm sheet of elastomer
composition 1A and then calendering 0.28 mm sheets of elastomer
composition 1B on both the top and bottom of the elastomer composition 1A
sheet. The total thickness of the three layer laminate was 1.13 mm.
Physical properties of the laminate were measured and the values are given
below in Table III. The edges of the laminate were seamed together as
described above. The original peel adhesion was 6.0 kN/m and after 7 days
at 70.degree. C. the value was 6.6 kN/m.
TABLE III
______________________________________
Machine Transverse
Direction
Direction
______________________________________
Properties Measured at 23.degree. C.
Modulus at 50% Elongation, (MPa)
8.5 5.7
Tensile Strength, (MPa)
9.9 8.2
Elongation at Break, (%)
290 420
Properties Measured at 70.degree. C.
Modulus at 59% Elongation, (MPa)
2.6 1.9
Tensile Strength, (MPa)
3.5 2.3
Elongation at Break, (%)
165 270
______________________________________
Samples of the three-layer laminate were cured following the same procedure
described above for the two-layer laminate. The modulus at 50% elongation
measured at 70.degree. C. in the transverse direction is shown in Table
IV.
TABLE IV
______________________________________
Modulus at 50% elongation (MPa)
______________________________________
0 Days 1.9
After 14 Days
2.5
After 30 Days
2.9
After 60 Days
2.8
After 90 Days
3.1
______________________________________
From the above it can be seen that the curable laminate has adequate
strength for installation as roofing and that it is strong enough to
withstand foot traffic even in its uncured state. Also, data indicate that
it forms strong heat weldable seams. Further, the laminate achieved about
80% of its cure at 70.degree. C. within 30 days.
EXAMPLE 2
An elastomer compound 2 was prepared using the procedure described in
Example 1 and containing 100 parts Polymer Composition A, 140 parts carbon
black, 30 parts paraffinic petroleum oil, 0.1 parts stearic acid, 3 parts
zinc oxide and 1.6 parts zinc dimethyldithiocarbamate. The Mooney scorch
at 150.degree. C. was measured. The minimum was 30 and after 30 minutes
there was a zero point rise.
A two layer laminate was produced using the calendar procedure described
above in Example 1 by calendering a 0.57 mm thick sheet of elastomer
compound 1A of Example 1 and 0.57 mm thick sheet of elastomer compound 2.
Physical properties of the curable laminate were measured at 23.degree. C.
and at 70.degree. C., according to ASTM D412 in both machine and
transverse directions. Results are shown in Table V.
TABLE V
______________________________________
Machine Transverse
Direction
Direction
______________________________________
Properties Measured at 23.degree. C.
Modulus at 50% Elongation, (MPa)
6.0 5.2
Tensile Strength, (MPa)
9.6 8.3
Elongation at Break, (%)
290 390
Properties Measured at 70.degree. C.
Modulus at 50% 2.5 2.1
Tensile Strength, (MPa)
3.2 2.4
Elongation at Break, (%)
200 265
______________________________________
Laminate samples prepared as described above were placed in an oven heated
to 70.degree. C. The modulus at 50% elongation measured at 70.degree. C.
in the transverse direction was determined after the time shown in Table
VI.
TABLE VI
______________________________________
Modulus at 50% Elongation, (MPa)
______________________________________
0 Days 2.1
After 14 Days
2.8
After 30 Days
2.7
After 60 Days
2.8
______________________________________
EXAMPLE 3
An elastomer compound 3A was prepared using the procedure described above
in Example 1 except that the compound was dumped from the mixer when the
temperature reached 140.degree.-150.degree. C. The compound contained 100
parts Polymer Composition D, 140 parts carbon black, 30 parts paraffinic
petroleum oil, 0.16 parts stearic acid, 3 parts zinc oxide, 1 part
elemental sulfur and 0.3 parts mercaptobenzothiazole. The Mooney scorch at
150.degree. C. was measured. The minimum was 27 and there was 10 point
rise in 30 minutes.
A second elastomer compound 3B was prepared in the same manner described
above and contained 100 parts Polymer Composition D, 140 carbon black, 30
parts paraffinic petroleum oil, 0.18 parts stearic acid, 3 parts zinc
oxide, 0.7 parts mercaptobenzothiazole and 1 part zinc
dibutyldithiocarbamate. The Mooney scorch at 150.degree. C. was measured.
The minimum was 24 and there was a zero point rise in 30 minutes.
A two-layer laminate was produced using the procedure described in Example
1 except that the calendar rolls were heated to 135.degree.-145.degree. C.
The thickness of each layer was 0.57 mm.
Physical properties of the curable laminate were measured, according to
ASTM D412 in both the machine and transverse directions. Results are shown
in Table VII.
TABLE VII
______________________________________
Machine Transverse
Direction
Direction
______________________________________
Properties Measured at 23.degree. C.
Modulus at 50% Elongation, (MPa)
6.8 5.8
Tensile Strength, (MPa)
9.6 8.5
Elongation at Break, (%)
280 370
Properties Measured at 70.degree. C.
Modulus at 50% Elongation, (MPa)
3.2 2.8
Tensile Strength, (MPa)
4.3 3.4
Elongation at Break, (%)
200 250
______________________________________
Laminate samples prepared as described above in Example 1 were placed in an
oven heated to 70.degree. C. The modulus at 50% elongation measured at
70.degree. C. in the transverse direction was determined after the time
shown in Table VIII.
TABLE VIII
______________________________________
Modulus at 50% Elongation, (MPa)
______________________________________
0 Days 2.8
After 14 Days
3.4
After 30 Days
3.4
After 60 Days
3.7
After 90 Days
3.7
______________________________________
EXAMPLE 4
An elastomer compound 4A was prepared using the procedure described in
Example 1 and containing 100 parts Polymer Composition B, 140 parts carbon
black, 30 parts paraffinic petroleum oil, 0.16 parts stearic acid, 3 parts
zinc oxide, and 1 part elemental sulfur. The Mooney scorch at 150.degree.
C. was measured. The minimum was 40 and there was zero point rise in 30
minutes.
A second elastomer compound 4B was prepared in the same manner and
contained 100 parts Polymer Composition B, 140 carbon black, 30 parts
paraffinic petroleum oil, 0.17 parts stearic acid, 3 parts zinc oxide, 0.1
parts mercaptobenzothiazole and 1 part zinc dibutyldithiocarbamate. The
Mooney scorch at 150.degree. C. was measured. The minimum was 36 and there
was a zero point rise in 30 minutes.
A two-layer laminate was produced using the procedure described in Example
1. The thickness of each layer was 0.57 mm.
Physical properties of the curable laminate were measured, according to
ASTM D412 in both the machine and transverse directions. Results are shown
in Table IX.
TABLE IX
______________________________________
Machine Transverse
Direction
Direction
______________________________________
Properties Measured at 23.degree. C.
Modulus at 50% Elongation, (MPa)
5.2 4.5
Tensile Strength, (MPa)
9.0 7.7
Elongation at Break, (%)
320 440
Properties Measured at 70.degree. C.
Modulus at 50% Elongation, (MPa)
1.7 1.4
Tensile Strength, (MPa)
2.0 1.7
Elongation at Break, (%)
135 275
______________________________________
Laminate samples prepared as described above in Example 1 were placed in an
oven heated to 70.degree. C. The modulus at 50% elongation measured at
70.degree. C. in the transverse direction was determined after the times
shown in Table X.
TABLE X
______________________________________
Modulus at 50% Elongation, (MPa)
______________________________________
0 Days 1.4
After 14 Days
1.9
After 30 Days
1.9
After 60 Days
1.9
______________________________________
EXAMPLE 5
An elastomer compound 5A was prepared using the procedure described in
Example 1 and containing 100 parts Polymer Composition C, 140 parts carbon
black, 30 parts paraffinic petroleum oil, 0.16 parts stearic acid, 3 parts
zinc oxide, and 1 part elemental sulfur. The Mooney scorch at 150.degree.
C. was measured. The minimum was 32 and there was a 10 point rise in 30
minutes.
A second elastomer compound 5B was prepared in the same manner as described
above and contained 100 parts Polymer Composition C, 140 carbon black, 30
parts paraffinic petroleum oil, 0.17 parts stearic acid, 3 parts zinc
oxide, 0.1 parts mercaptobenzothiazole and 1 part zinc
dibutyldithiocarbamate. The Mooney scorch at 150.degree. C. was measured.
The minimum was 30 and there was a zero point rise in 30 minutes.
A two-layer laminate was produced using the procedure described in Example
1. The thickness of each layer was 0.57 mm.
Physical properties of the curable laminate were measured, according to
ASTM D412 in both the machine and transverse directions. Results are shown
in Table XI.
TABLE XI
______________________________________
Machine Transverse
Direction
Direction
______________________________________
Properties Measured at 23.degree. C.
Modulus at 50% Elongation, (MPa)
4.5 4.1
Tensile Strength, (MPa)
7.2 6.5
Elongation at Break, (%)
440 550
Properties Measured at 70.degree. C.
Modulus at 50% Elongation, (MPa)
1.7 1.6
Tensile Strength, (MPa)
2.0 1.6
Elongation at Break, (%)
245 255
______________________________________
Laminate samples prepared as described above in Example 1 were placed in an
oven heated to 70.degree. C. The modulus at 50% elongation measured at
70.degree. C. in the transverse direction was determined after the time
shown in Table XII.
TABLE XII
______________________________________
Modulus at 50% Elongation, (MPa)
______________________________________
0 Days 1.6
After 14 Days
2.0
After 30 Days
2.1
After 60 Days
1.9
______________________________________
EXAMPLE 6
An elastomer compound 6A was prepared using the procedure described in
Example 1 except that the compound was dumped from the mixer when the
temperature reached 140.degree.-150.degree. C. The compound contained 100
parts Polymer Composition D, 140 parts carbon black, 30 parts paraffinic
petroleum oil, 0.2 parts stearic acid, and 1 part elemental sulfur.
A second elastomer compound 6B was prepared in the same manner as described
above and contained 100 parts Polymer Composition D, 140 carbon black, 30
parts paraffinic petroleum oil, 0.17 parts stearic acid, 1 part
mercaptobenzothiazole and 1 part zinc dibutyldithiocarbamate.
A two-layer laminate was produced using the procedure described in Example
1 except that the calendar rolls were heated to 135.degree.-145.degree. C.
The thickness of each layer was 0.57 mm.
Physical properties of the curable laminate were measured, according to
ASTM D412 in both the machine and transverse directions. Results are shown
in Table XII.
TABLE XII
______________________________________
Machine Transverse
Direction
Direction
______________________________________
Properties Measured at 23.degree. C.
Modulus at 50% Elongation, (MPa)
6.6 6.0
Tensile Strength, (MPa)
9.7 8.7
Elongation at Break, (%)
320 360
Properties Measured at 70.degree. C.
Modulus at 50% Elongation, (MPa)
2.8 2.3
Tensile Strength, (MPa)
3.8 2.8
Elongation at Break, (%)
240 290
______________________________________
Laminate samples prepared as described above in Example 1 were placed in an
oven heated to 70.degree. C. The modulus at 50% elongation measured at
70.degree. C. in the transverse direction was determined after the times
shown in Table XIV.
TABLE XIV
______________________________________
Modulus at 50% Elongation, (MPa)
______________________________________
0 Days 2.3
After 14 Days
3.1
After 30 Days
3.5
After 60 Days
3.6
After 90 Days
3.5
______________________________________
EXAMPLE 7
An elastomer compound 7A was prepared using the procedure described in
Example 1. The compound contained 100 parts Polymer Composition E, 150
parts carbon black, 40 parts haphthenic petroleum oil (Circosol 4240), 0.1
parts stearic acid, 3 parts zinc oxide, 1.6 parts elemental sulfur and 0.5
parts mercaptobenzothiazole. The Mooney scorch at 132.degree. C. was
measured. The minimum was 35 and there was a zero point rise in 20
minutes.
A second elastomer compound 7B was prepared in the same manner. The
compound contained 100 parts Polymer Composition E, 150 parts carbon
black, 40 parts naphthenic petroleum oil (Circosol 4240), 0.1 parts
stearic acid, 3 parts zinc oxide, 0.5 parts mercaptobenzothiazole and 1
part zinc dibutyldithiocarbamate.
Laminate samples prepared as described above in Example 1 were placed in an
oven heated to 70.degree. C. The modulus at 50% elongation measured at
23.degree. C. and at 70.degree. C. in the transverse direction was
determined after the times shown in the Table XV.
TABLE XV
______________________________________
Modulus at 50% Elonqation, (MPa)
23.degree. C.
70.degree. C.
______________________________________
0 Days 2.8 0.9
After 14 Days 3.1 1.4
After 28 Days 3.1 1.5
After 56 Days 3.5 1.7
After 112 Days 3.7 1.8
______________________________________
Top